Two-Stage Ditch Floodplains Enhance N-Removal Capacity and Reduce Turbidity and Dissolved P in Agricultural Streams

摘要: Two-stage ditches represent an emerging management strategy in artificially drained agricultural landscapes that mimics natural floodplains and has the potential to improve water quality. We assessed for two-stage ditch reduce sediment nutrient export by measuring column turbidity, nitrate (NO3−), ammonium (NH4+), soluble reactive phosphorus (SRP) concentrations, denitrification rates. During 2009-2010, we compared reaches with upstream conventional trapezoid design six streams. At base flow, these short (<600 m) reduced SRP concentrations 3-53%, but did not significantly NO3− due very high loads. The also decreased turbidity 15-82%, suggesting suspended during floodplain inundation. Reach-scale N-removal increased 3-24 fold inundation bioreactive surface area Inundation frequency varied bench height, lower benches being flooded more frequently, resulting higher annual N-removal. found both soil organic matter rates were on older floodplains. Finally, influence of among streams years variation stream discharge, loads, rates, which should be considered implementation optimize quality benefits.